Titanium base alloys



United States PatentC TITANIUM BASE ALLOYS Stanley -Abkowitzv and Lee S; Busch,.:Warren, .Ohio, as--- signors to Mallory-SharonTitaniumCorporation, Niles, one; a corporation of Delaware No Drawing. Application August 16,1955.

SeriaI No. 528,819

6Claimsn (CL' 75- -1755)" The inventionirelates to titanium-base'alloys and'more particularly to titanium-base alloys containing;aluminum,-i. vanadium, chromium and'molybdenum.

The present invention comprises the discovery 'that" the additiom "to" titanium aluminume alloys of relatively sm allamounts of: vanadium, chromium and molybdenum 2O efiectsamarlced improvemen-Mn the propertiesiof such alloys of an aluminum content of3% to 5%. 'The alloys show a. rare combination: of extraordinary strength with-adequate ductility.

The: useof titanium-as a-stru'ctural material is'lir niteda by its relatively low strength and: high-cost; for Whichn.

reason it has been found-desirable-to all-0y, titanium'wit'h such other metals as will increase the=strehgth=ancbpref+a crabl-y effect-some reduction-in the itotal COSi-rAlUI'lli-T.

num=is a metal wellsuitedto these objectives, beinIg-lcnviiniweight, relatively low in cost; and havin'g:a5 materials. strengthening effect 1 on titanium.

However, the-amount of aluminum alone thatrcanzh'e added to: titanium is "limited 'by its adverse; eifectcon' u ductility. Binary alloys of titanium with more than 5%?- found" that suchan alloy without tin is superior to thetx: same=.-alloy.with .tin, for both plate and sheet:applications,. o

as it producesimproved toughness "in the plate and im-" proved bend properties in the sheet; Also, it is desira-e. 1 bleto-elirninate tin from .theialloy not only .for the-reason that'itis a strategic element, but because itincreases, the density. of the material, and, because of itsrelatively low melting point it is difficult to handle in the melt.

It is an object of the invention toprovide 'strong,w-duc;-x tile-alloys of titanium.

Another object .isto provide I titanium alloys which are? heat treatable to high strength.

A further object is toprovide a titanium,"aluminum,' vanadium, chromium, molybdenum alloy. which isxsuita m ble.for use in plate or sheetforrna A still furtherzobject is to provide-such an alloy which ice 2! allyj which'isi soft inthefas-quenched condition withfigoejd bend propertiesin the sheet form.

A further object is to provide'such' a" titanium alloy? which is age hardenable by following the heattreattnent with a eing at 9o0'te not)??? A still further -object istd'proyide a titanium" alloy of f' this 'ch'aracter in whili the' ductility *of thehardned ma teria'l is very satisfactory and- 'in -Which the tensile f strength approaches 200,000 lbs. per square inch? Other objects and advantages -of the invention will be apparentin view of the following deteailed descriptions thereof? In general} thefirivention reIa t to" quinary" all-o'y'sof titanium, aluminum, vanadium, chromium and molybde num, comprising..fr.orn .3 to .5..%..aluminum,from .1 to. 2%...-

vanadium,..from .a.,trace to 1% Chromium (preferably fIOl'lF-S*i0.'1%=), fl0fil'la traceato 1% molybdenum (preferablyfrom-v5- to 1%") the-bala-nce being all titaniumr' Titanium; aluminum, vanadium, chromium,- imo'lybde m num .alloys-comingiwithin ,theabove range are hea'ttreate? able to high trengthand maintain satisfactory andgood notch toughness desirable in plate form. The alloy is soft-tin the 'a-squenched' condition with good b'end prop V ertie'sdesirable in the' s'hee'tform;

This alloy inay be 'hea't treated by l'ieatfng f-a t IZQQ w- 1700 1 fCfl a halffiblfi 'fihdWhiP-Wiif q-ilil'ehii'l 7*; After this treatment the alloy is age hardenable bye-gang for two hours between 900 and r1 F. and air cooling. The ductility of thisuhardenedmaterial is ve1y.satisfac..

tory; haVingyapprogtirnately 10% elongation wit hflensi'le strength approaching =2o0,000'-115s: per "square inch:

The following are examples of titanium, alum'itiutn', vanadium; chromium molybdenunr-alloys;coming'within'" the above range; which: haveibeen producedgnheat treated and"evaluated'*for mechanical "properties.

Example"I;+3%""aluniinuin, 1 6%" vanadium, ,5'%"

' chromium; .5% molybdenum and the-tbalan'ce.essentiallyiii all titanium;

chromium, .5 .molybdenum -3I1dkth6'. balance ,-essen.tiall-y all .titanium.

Examplew3I -5%, .aluminum, il /2 vanadium, 1. 5%

chroniurn, 5%. molybdenum andatheabalanceessentially--- all titanium.

Example 4.4% aluminum,.2%-.-vanadium, 1% chrominum, 1% molybdenum andthe balance essentially all titanium:

These all'oys'may be preparetl fro'rtn either ieomi'n'etciai'l titanium or high purity titanium. Where prepared-front commercial -titanium,--a-typiea1analysis-of me-material in addition-to.titaniumgaaluminum, :vanadiumachromium andmolybdenum,-is 0.02l%" C,"0'."01%% N 0.10% 0 and 0.005%"H However, the invention is not restrictedto the use of 'materla'l having the ty icatainterstitiaLJeveI-iin dicated a s the level *tnaybe of the-orderof0.-06%' 0.03%-N 0.15% 0 and 0.017 H An ingot-of tite /alloys of Example-Aswasscastpandihof forged intoi /3 rounds,-. andspecim'ens were'scutytherei from and heat ;:treated, and. evaluated for i-mechanicah properties of th'ezplate sform,'e:as -shown intheifollowingi. Table I.

TABLE I plate Ultimate 2% yield percent Percent Impact, Heat treatment Strength strength elong. area 40 F.

reduc. (Ft. Lb.)

1,600 E, 34 hr. AC 145.800 112, 000 17. 2 52. 4 19. 5 1,600 K, 14 hr. WQ, 142 300 101,200 18.0 50.9 19. 5 1,600 F., 56 hr. WQ and aged at 143 800 126.100 13.3 42.4 23. 5 l.100 F.. 2 hiv AC. 146. 100 130. 000 14. l 50. l 20. 5 1,600 F.. 14 hr. WQ and aged at 167, 500 136. 800 9.4 23.7 5 900 F., 2 hr. AC. 157.800 127. 200 10. 2 33. 7 12 1,300 F., 1 111'. AC (annealed). 132.800 124, 600 11.7 47. 4 20. 5

1 Two specimens.

TABLE II Heat treating data for 3% Al, I 6% V, .5 Cr, .5 Mo,

balance Ti, and evaluation for mechanical properties of sheet Heat Treatment Ultimate .2% yield percent Bend Strength strength elong. Test 1.500 F., hr. WQ, 110, 200 75,600 21. 1 3.2 T quenched and aged at 900 F., 2 hrs 133, 100 99, 400 12. 5 4.7 '1

An ingot of the alloy of Example 2 was cast, hot forged to sheet bars, hot rolled to 0.040" sheets, and specimens thereof were heat treated and evaluated for mechanical properties of the sheet form as shown on the following Table III.

TABLE IH Heat treating data for 4% A1, 1 .6% V, .5 Cr, .5 Mo, balance Ti, and evaluation for mechanical properties An ingot of the alloy of Example 3 was cast, hot forged to sheet bars, hot rolled to 0.040" sheets, and specimens thereof were heat treated and evaluated for mechanical properties of the sheet form as shown on the following Table IV.

TABLE IV Heat treating data for 5% Al, /2% V, .5 Cr, .5 Mo, balance Ti, and evaluation of mechanical properties of sheet Heat Treatment Ultimate .20; yield percent Bend Strength strength clong. Test 1,600 F., A 111'. W 134, 100 94. 600 10.4 5.9 T quenched and age at 900 F.', 2 hrs 157, 700 128, 200 10. 2 9.0 '1

In the same manner an ingot of the alloy of Example 4 was cast, hot forged to sheet bars, hot rolled to 0.040" sheets, and specimens were heat treated and evaluated for mechanical properties of sheet formas shown in the following Table V.

TABLE V Heat treating data for 4% Al, 2% V, 1% Cr, 1% Mo, balance Ti, and evaluation of mechanical properties of sheet Ultimate 2% yield per- Bend Heat Treatment Strength strength cent Test along.

l,600 F., 4 hr. WQ. 135, 000 95, 000 1 7.8 2.8 T quenched and aged at 900 F., 2 h 182, 150,000 10. 2 8.8 '1 1,650 R, Li hr. WQ an ged at 900 F., 2 his 195, 700 171, 000 10. 2 Brittle.

1 The low elongation in the as-quenched conditlnn is due to fracture occurring at the gauge mark. On the basis of the as-quenched properties of the low beta complex the true value should be better than 16% elongation. The good T bend adds to the validity of this analogy.

The alloys of the present invention are characterized by their good ductility and impact resistance at tensile strength of from about 150,000 p. s. i. to nearly 200,000 p. s. i., when heat treated and aged.

These alloys compare very favorably with the ternary alloy 6A1, 4V, balance Ti, which has become generally accepted throughout the titanium industry as a heat-treatable alloy. The successful use of this Al-4V alloy is somewhat limited in use because of its low hardenability, high strengths being limited to sections up to about two inches thick, and because of its poor formability and low heat-treat response in sheet thicknesses, T bends averaging 5-6T at best.

It appears that the Cr and Mo substitution in our complex alloys substantially improve the hardenability and response to heat treatment of the alloys. For comparative purposes, the 6Al4V alloy was investigated for heat-treat response in sheet form, and it was found that while the as-quenched strengths are somewhat higher for the 6Al4V alloy than for our Al--V complex alloys, the bend ductility of our complex alloys is superior in the as-quenched condition. Aging the 6Al4V alloy at 900 F. raises the strength level some 25,000 p. s. i., whereas aging our complex alloys improves the strength some 50,000 p. s. i. The highest aged strength consistent with good ductility is about 160,000 p. s. i. for the 6Al4V alloy and about 180,000 p. s. i. for our complex alloys.

The 4Al-2V--1Cr-1Mo alloy in plate form should produce improved properties for plate applications, especially armor plate when high impact strength at 130,000 p. s. i. yield is desired. The low beta complex such as 4Al--1.5V.5Cr--.5Mo alloy offers good ductility and low strength in the solution treated condition.

From the above it is evident that titanium, aluminium, vanadium, chromium, molybdenum alloys produced in accordance with the invention are heat treatable to high strength, and while in the as-quenched condition have good bend properties for sheet form, and are age hardenable so as to produce the best mechanical properties for plate form. The excellent strength and ductility of any of the 5 foregoing alloys render them highly desirable materials for many uses requiring high ratio of strength to weight.

In the foregoing description, certain terms have been used for brevity, clearness and understanding, but no unnecessary limitation are to be implied therefrom beyond the requirements of the prior art, because such words are used for descriptive purposes herein and are intended to be broadly construed.

Having now described the invention or discovery, the use of preferred embodiments thereof, and the advantageous new and useful results obtained thereby, it should be understood that the embodiments described are by way of typical examples only, and that the proportions of the several metals may be varied within the above range without departing from the invention as set forth in the 15 dium, 0.5 chromium, 0.5 molybdenum, balance tita- 25 mum.

5 1% chromium, 1% molybdenum, balance titanium.

6. An alloy consisting of from 3% to 5% Al, from 1% to 2% V, from 0.5% to 1% Cr, from 0.5% to 1% Mo, from 0.02% to 0.06% C, from 0.01% to 0.03% N from 0.10% to 0.15% 0 from 0.005% to 0.017% H 10 balance Ti.

References Cited in the file of this patent UNITED STATES PATENTS 2,700,607 Methe Jan. 25, 1955 2,711,960 Methe June 28, 1955 FOREIGN PATENTS 1,085,628 France -1 July 28, 1954 OTHER REFERENCES The Manufacture of Titanium Alloys, Larsen et 21., pages 52, 54, 70 and 82. Report #9, Titanium Project Navy Contract No. Noa(s) 51-006-c, P. R. Mallory & Co. Inc., Indianapolis, Ind., I anuary 26, 1952. 

1. AN ALLOY CONSISTING OF FROM 3% TO 5% ALUMINUM, FROM 1% TO 2% VANADIUM, FROM 0.5% TO 1% CHROMIUM, FROM 0.5% TO 1% MOLYBDENUM, BALANCE TITANIUM. 